• Title/Summary/Keyword: crash

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Impacts of Pre-signals on Traffic Crashes at 4-leg Signalized Intersections (전방신호기가 교통사고에 미치는 영향 연구)

  • Kim, Byeongeun;Lee, Youngihn
    • International Journal of Highway Engineering
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    • v.15 no.4
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    • pp.135-146
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    • 2013
  • PURPOSES : This study aimed to analyze the impact the operation of pre-signals at 4-leg signalized intersections and present primary environmental factors of roads that need to be considered in the installation of pre-signals. METHODS : Shift of proportions safety effectiveness evaluation method which assesses shifts in proportions of target collision types to determine safety effectiveness was applied to analyze traffic crash by types. Also, Empirical Bayes before/after safety effectiveness evaluation method was adapted to analyze the impact pre-signal installation. Negative binomial regression was conducted to determine SPF(safety performance function). RESULTS : Pre-signals are effective in reducing the number of head on, right angle and sideswipe collisions and both the total number of personal injury crashes and severe crashes. Also, it is deemed that each factor used as an independent variable for the SPF model has strong correlation with the total number of personal injury crashes and severe crashes, and impacts general traffic crashes as a whole. CONCLUSIONS: This study suggests the following should be considered in pre-signal installation on intersections. 1) U-turns allowed in the front and rear 2) A high number of roads that connect to the intersection 3) Many right-turn traffic flows 4) Crosswalks installed in the front and rear 5) Insufficient left-turn lanes compared to left-turn traffic flows or no left-turn-only lane.

Dynamic Characteristic Analysis of MR Impact Damper for Vehicle System (차량용 MR 충격댐퍼의 동특성 해석)

  • Song, Hyun-Jeong;Woo, David;Choi, Seung-Bok
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2006.05a
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    • pp.147-152
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    • 2006
  • This paper presents the dynamic characteristics of MR impact damper for vehicle collision system. Various types of mechanism have been proposed for reduce transmitted force to vehicle chassis and finally protect occupants from injury. In the case of frontal collision, the bumper make main role of isolation material for collision attenuation. In this study, proposed bumper system composed of MR impact damper and structures. The MR impact damper is to adopted MR fluid which has reversible properties with applied magnetic field. MR fluid operates under flow mode with Bingham flow and bellows is used for generation of fluid flow. Mathematical model of MR impact damper incorporated with MR fluid is established. Field dependent damping force is investigated with time and frequency domain. The MR impact damper is then incorporated with vehicle crash system. The governing equation of motion of vehicle model is formulated considering occupant model. Dynamic characteristics of vehicle collision system investigated with computer simulation.

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Optimum Design of an Automobile Front Bumper Using Orthogonal Array (직교배열표를 이용한 승용차 앞 범퍼의 최적설계)

  • 이권희;주원식
    • Transactions of the Korean Society of Automotive Engineers
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    • v.10 no.6
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    • pp.125-132
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    • 2002
  • Bumpers are structural components to reduce physical damage to the front and rear ends of a passenger motor vehicle from low speed collisions. Damage assessment and the protectiveness are the commonly used designing criteria but in this study, relative displacements of the bumper are examined. To absorb the crash energy without significant damage to the bumper itself, foam material is installed between fascia and beam. However, it is not easy to predict the exact displacements generated in bumper structures through FEM because the compressive stress-strain curve of a foam material depends on strain rates that deviates significantly on each trial. Under this uncertain condition, a range of displacements is calculated and the optimum design is performed using the design of experiments. The result will be used to find the design that minimizes the weight within displacement constraints. The orthogonal array of L9 is introduced to find the optimum of the design variables that considers the thickness of inner beam, outer beam and stay, This study will suggest the design procedure of a front bumper using the uncertain stress-strain curve of a foam material.

A New Airbag Modeling Using a Sphere and a Torus and the Occupant Analysis in the Out-of-position (구와 원환체를 이용한 에어백의 모델링 및 비정상위치시의 승객 거동 해석)

  • 임재문;김창환;박경진
    • Transactions of the Korean Society of Automotive Engineers
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    • v.4 no.1
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    • pp.96-109
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    • 1996
  • The airbag system is known to be extremely efficient for the protection in an automobile crash. The performance of the airbag system is evaluated by real tests. However, the test is very difficult and expensive. Therefore, the computational simulations are carried out with low cost. The airbag analysis is included in the anlysis of the full-car crashworthiness. The behavior of the airbag can be predicted by a thermodynamic analysis. The contact force between the occupant and the airbag is calculated from the contact volume and the pressure in the airbag. The injury rate is evaluated from the contact force and the acceleration of dummies. So far, the contact is defined after the airgag is fully inflated. In many cases, the occupant is seated in the out-of-position and the contact can happen during the inflation process. A new algorithm has been developed for the out-of-position. To describe the inflation process precisely, the airbag is defined by a sphere and a torus. The injury is evaluated for the contact happened at any time. The developed algorithm is coded and interfaced with an existing software in the public domain. The full-car modeling is adopted from the previous study which is tuned for the regular position and real tests. Numerical experimentation have been carried out with a couple of dummies in the out-of-position and the injury processes are analyzed.

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Comparison of Rapid Braking Characteristics between an Expert Driver and a General Person (전문가와 일반인의 급제동 특성 및 바퀴 잠김 속도 비교)

  • Kim, Kee-Nam;Lee, Ji-Hoon;Kim, Min-Seok;Yoo, Wan-Suk
    • Transactions of the Korean Society of Automotive Engineers
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    • v.17 no.1
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    • pp.12-18
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    • 2009
  • Skid mark and coefficient of friction are usually utilized to calculate the velocity and behavior of vehicles. For a critical case such as traffic accident reconstruction, however, the initial velocity of the car should be calculated precisely. In this study, in order to estimate the speed at the brake onset, rapid braking tests were executed on the proving ground. We compared with a skid length and wheel locking time of an expert driver and a general person. We verified that the skid mark of expert driver occurs longer than general person's. A new method is proposed to determine the speed of a vehicle at the brake onset of maximum braking, which could be applied to a reconstruction of vehicle with Non-ABS.

A Study on Shape Design of the Passenger Airbag for Efficiency Improvement (조수석 에어백 성능 개선을 위한 형상 설계연구)

  • Yang, Sunghoon;Yim, Jonghyun;Kim, Seungki;Chae, Soo-Won
    • Transactions of the Korean Society of Automotive Engineers
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    • v.25 no.2
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    • pp.242-249
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    • 2017
  • In this study, the relationship between the shape of a passenger airbag and the possibility of injury is analyzed using the Taguchi method. The optimal shape combination is proposed for a design guideline that can reduce the possibility of injury to the dummy. The airbag FE model for analysis is obtained using a CAD system that can change the shape through several independent variables. The widths of the left / right, top / bottom, and back / forth direction of the airbag shape are set as the design factors, and the effect of the combination injury probability according to the shape is analyzed. The minimum geometric combinations are obtained using the orthogonal array method. The signal to noise ratio is calculated and the optimal shape combination is obtained through sensitivity analysis. The obtained optimal shape combination is compared with the possibility of injury of the initial airbag shape to confirm improved airbag performance.

A study of rear seat belts geometric characteristics for rear seated occupants protections (뒷좌석 승객 보호를 위한 안전띠의 기하학적 특성에 대한 연구)

  • Youn, Younghan;Park, Jiyang;Lee, Seungsang;Kim, Minyoung
    • Journal of Auto-vehicle Safety Association
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    • v.7 no.1
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    • pp.45-50
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    • 2015
  • The protection of frontal seat passengers in both driver and front seated occupant has been more focused from the auto industries as well as regulatory bodies more than 40 years. Recently, their interests have been extended to rear seat occupants especially children and female occupants. However, the current available safety devices for the rear seat occupants are seat belt only. According to the previous researchers, the injury level of the rear seat passengers tend to be higher than the injury level of the frontal seat passengers. In this study, the optimal location of seat belts anchorages to enhance rear passengers crashworthiness are studied. FEM models are designed in accordance with regulation of KMVSS102, UN R44, UN R16, and UN R14. and three point belts are fitted on the HybridIII 5th percentile dummy and HybridIII 50th percentile dummy. The combined injury value used HIC15, Nij, Chest deflection, Femur force are used to evaluate rear seat belt anchorage optimal locations.

Effect of Microstructure on Dynamic Tensile Characteristics of SPRC440 Sheet (SPRC440 강판재의 미세조직 구성이 동적 인장 특성에 미치는 영향)

  • Lee, S.H.;Rhyim, Y.M.;Lee, J.H.;Kim, I.B.;Kim, Y.D.
    • Transactions of Materials Processing
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    • v.20 no.4
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    • pp.309-315
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    • 2011
  • The behavior of metallic materials at high strain rates shows different characteristics from those in quasi-static deformation. Therefore, the strain rate should be considered when simulating crash events. The objective of this paper is to evaluate the dynamic tensile characteristics of SPRC440 as a function of the volume fraction of phases. As-received SPRC440 is composed of ferrite and pearlite phases. However, ferrite and martensite phases were observed after heat treatment at $730^{\circ}C$ and $780^{\circ}C$ for 5 minutes, as expected by calculations based on the curves from dilatometry tests. High cross-head speed tensile tests were performed to acquire strain-stress curves at various strain rates ranging from 0.001 to $300\;s^{-1}$, which are typical in real vehicle crashes. It was observed that the flow stress increases with the strain rate and this trend was more pronounced in the as-received specimens consisting of ferrite and pearlite phases. It is speculated that the dislocation density in each phase has an influence on the strain rate sensitivity.

Dynamic tensile characteristics of SUS304L steel sheets (SUS304계열 강판의 동적인장특성)

  • Kim, J.S.;Huh, H.;Lee, J.W.;Kwon, T.S.
    • Proceedings of the Korean Society for Technology of Plasticity Conference
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    • 2007.10a
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    • pp.360-363
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    • 2007
  • This paper deals with the dynamic tensile characteristics of the steel sheets for structural members of a train. Train accidents occurs rarely but lead to many casualties and economical loss. Therefore the safety of the train becomes important during the train crash. The dynamic tensile characteristics of the steel sheets are indispensable to analyze the structural crashworthiness. Current research reports the stress-strain curves, fracture elongation and strain rate sensitivities evaluated at the various strain rates especially for SUS304L-ST and SUS304L-LT steel sheets. The results include the difference in the dynamic tensile characteristics of both rolling and transverse directions. Dynamic tensile tests were performed at the strain rates ranging from 0.003/sec to 200/sec using High Speed Material Testing Machine. The materials tested in this research shows interesting behavior at the low strain rates. The strain hardening exponent decreases remarkably while the yield strength increases.

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Comparative Crashworthiness Assessment of the ULSAB-AVC Model with Advance High Strength Steel and with Low Strength Steel (고강도 강판 ULSAB-AVC 모델과 일반강판 모델의 충돌성능 비교 평가)

  • Yoon, Jong-Heon;Huh, Hoon;Kim, Se-Ho;Kim, Hong-Kee;Park, Seung-Ho
    • Transactions of the Korean Society of Automotive Engineers
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    • v.14 no.3
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    • pp.22-27
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    • 2006
  • As the regulation and assessment program for safety of passengers become stringent, automakers are required to develop lighter and safer vehicles. In order to fulfill both requirements which conflict with each other, automobile and steel companies have proposed the application of AHSS(Advance High Strength Steel) such as DP, TRIP and martensite steel. ULSAB-AVC model is one of the most remarkable reactions to offer solutions with the use of steel for the challenge to improve simultaneously the fuel efficiency, passenger safety, vehicle performance and affordability. This paper is concerned with the crash analysis of ULSAB-AVC model according to the US-SINCAP in order to compare the effectiveness between the model with AHSS and that with conventional steels. The crashworthiness is investigated by comparing the deformed shape of the cabin room, the energy absorption characteristics and the intrusion velocity of a car.